Time and date picker adjusts time based on timezone

[galingong]

Description

time_picker field would adjust the value displayed in the field based on OS/browser timezone ie. will not display the value stored in the DB, but treats that value as if it was UTC and the displayed value was local. Value in store is correct so it should be something related to frontend/flatpickr.js.

Edit: date_picker with time is also affected.

Steps to reproduce

Set your OS timezone to something other than UTC and compare DB stored value and the field.

Expected result

No timezone adjustment

Actual result

Value in field offset by timezone

Versions

Twill version: 2.3.0
Laravel version: 10

[galingong]

It's probably because in DatePicker.vue on line 152 date-fns.parse is called with date + 'Z' and format + 'X' so the parsed value would be offset. Removing the Z (and since it's not needed anymore, also the X from format) seems to resolve the issue.

Edit: Had to also edit flatpickr format on line 135 to dateFormat: self.enableTime ? 'Y-m-d H:i' : 'Y-m-d' to completely resolve the problem.